Little voice

I do not understand that in many occasions when I want to speak, there is a little voice telling me to stop. The little voice told me that I should not be agressive. The little voice told me that I should keep silent. The little voice keeps telling me that I could not speak well. The little voice keeps telling me I will stutter. What is the little voice?
I sometimes was hypnotized by the little voice. I am told that I will stutter, so I do stutter. The little voice told me that I should not be aggressive, so I hold myself back.
There is another subtle cue telling me that I should not produce sounds. In my unconsciousness, I am afraid of letting my voice to be heard, so I stutter. I could feel it sometimes.
If I could not get other body's attention, I feel that I could not talk. I do not know if other person feel the same way. Usually, before I talk, I say Ah, Ah, Ah couple of times. The purpose of these Ah's is to get other body's attention.

How can I get rid of the control of the little voice?